PoliGrid: Photovoltaic Inverters Supporting Power Grid Flexibility
An important achievement for PoliGrid, Politecnico di Milano’s smart grid: during the night between 8 and 9 September 2026, from 1:00 a.m. to 5:00 a.m., a reactive power regulation service was provided to Milan’s distribution grid using exclusively the inverters of the photovoltaic systems installed on the campus buildings.
PoliGrid provided 500 kVAr of reactive power regulation as part of the MiNDFlex pilot project by Unareti. To the research group’s knowledge, this is the first provision in Italy of a market-based reactive power flexibility service.
A particularly interesting aspect of the experiment is that the service was provided during nighttime hours: in the absence of photovoltaic generation, the inverters can in fact be used to deliver services supporting electricity grid management, making use of infrastructure that is already available without interfering with energy production.
Reactive power dispatch was managed through LePo, the Energy Management System developed by the Department of Energy of Politecnico di Milano and LEAP, and integrated into the Optimo IoT environment.
The result marks a further development of the activities launched in 2024 within MiNDFlex, when PoliGrid had already been enabled to provide active power flexibility services. The new experiment extends these capabilities to reactive power regulation as well.
The experience demonstrates how inverters associated with renewable energy systems can play a role that goes beyond simply feeding electricity into the grid, actively contributing to the regulation and management of distribution networks. This function is expected to become increasingly important in an electricity system characterized by a growing share of renewable energy sources.
With the particular contribution of researchers Andrea Scrocca and Edoardo Daccò, the experiment is part of the research activities of the SIMBIOsi project and is led by the Electrical Systems for Energy and Transport (ESET) research group of the Department of Energy at Politecnico di Milano.
“This experiment shows how distributed energy resources can shift from being a source of challenges for electricity grid management to becoming part of the solution. Leveraging capabilities that are already available within the grid, such as photovoltaic inverters for reactive power regulation, can create value for service providers while also helping distribution system operators reduce investments and the overall costs of the electricity system.”
